Internal combustion engines, including diesel engines, may produce regulated emissions, such as nitrogen oxides (NOx), and solid particulate matter which may also be referred to as soot or smoke. To control emissions, diesel engines may include a variety of specially calibrated systems such as Exhaust Gas Recirculation (EGR) systems, Selective Catalytic Reduction (SCR) systems, Diesel Particulate Filter (DPF) systems, and combinations thereof. An engine control module (ECM) is often used to calibrate and control these emission control systems, as well as a large variety of engine control parameters, in a carefully balanced approach that weighs fuel efficiency against the regulation of emissions.
U.S. Pat. No. 7,861,518 describes an engine controller that considers the cost of operating a combustion engine and the cost of operating an SCR system in establishing the parameters by which the diesel engine will operate. Cost-efficiency of the system is determined by controlling engine parameters, including cooled EGR airflow, fuel injection timing, fuel injection pressure, and air-to-fuel ratio, as well as the volume of reductant used in the SCR system. However, the control of air intake valve timing is not considered.
Intake Valve Actuation (IVA) may be used in internal combustion engines to, for example, increase fuel efficiency. By controlling the closure timing of the intake valves, for example, the volumetric efficiency of a diesel engine may be adjusted. One of the advantages of this adjustment is achievement of better indicated thermal efficiency at part loads while IVA maintains relatively low peak cylinder pressure at high loads. Peak cylinder pressure directly impacts combustion temperature in cylinders, and hence impacts the engine out brake-specific NOx (BSNOx) emission. Because tailpipe BSNOx is determined by engine out BSNOx and SCR conversion performance, IVA may have a direct impact on the use of a reductant, or Diesel Emission Fluid (DEF) in the SCR system. In addition, IVA has a direct impact on the exhaust recirculation flow of the EGR system due to the IVA influence on the intake manifold pressure. Conventional IVA control performs tasks according to a set logic as predetermined by engine calibration maps, although the price of diesel fuel and reductant, or Diesel Emission Fluid (DEF), may change or vary across different regions and in different seasons.
The present disclosure is directed to address one or more of the issues set forth above with respect to conventional diesel engines, in addition to other problems in the art.